What is wrong with my blade?

[CptanPanic]

I have noticed that when I make a cut on my bt3100 the edge is not flat. I used to think that it was just not staying on the fence perfectly, but now I am not sure. For example today I cut a small piece of plywood as a test, and when I put the two pieces next to each other, they don't fit perfectly together. It seems like the blade sometimes goes out of round, and cuts a wider kerf than other times. Does this make sense? The blade I am using is the one that came with it that was made in Italy. Should I get another blade, or what is going on.
Thanks,
CP

[Jim Boyd]

When you say flat, do you mean parallel to the fence or the blade. Horizontal or verticle?

[CptanPanic]

When you say flat, do you mean parallel to the fence or the blade. Horizontal or verticle?

Flat along the cut edge.

[Wood_workur]

Is the blade placed snugly against the washers? (no sawdust on the washers/blade[where is contacts the washers])

[cgallery]

Are you thinking your blade wobbles? If so, raise your blade and start the saw for only a second or two. When you turn it off, watch as it slows to see if you can perceive any wobble.

Or, uplug the saw and raise the blade as high as it will go. Drive a small nail halfway into the end of a 2x2. Clamp the 2x2 with the nail to the SMT's fence so that the blade is touching the nail head. Rotate the blade slowly (don't turn the saw on) and observe the distance between the nail and the blade. Make adjustments to the clamped 2x2 so you can find the high and low spots on the blade.

If you observe any wobble to the blade, then disassemble the blade nut, washers, and spacers and clean thoroughly (and clean the blade, too) and reassemble. Now perform the same test. If there is still wobble, see if you can source another blade and test again. If there is still wobble you need to investigate your arbor spacers and washers. You can use a straight-edge on its edge and a flat surface like a granite counter-top to determine if they are flat. They need to be very flat.

If they are flat, you may have excessive arbor runout or a slipped belt. However, I think dirt on the washers/spacers/blade are much more common.

Thanks,
Phil

[cgallery]

Oh, and here is another thought. If you are saying that you don't get a straight cut using your fence, make certain the edge you're holding against the fence is perfectly straight. Some of the pre-cut sheet goods I have purchased from a local lumber yard aren't cut straight. They're off by as much as 1/32" over 4'. I have to joint them to get them straight before I can cut them further on my saw.

[Jim Boyd]

And also make sure the end of the fence is locked. Sometime I had the rear clamp get out of the groove and left the back of the fence loose. Took a while to find the problem the first time.

[LCHIEN]

I would say that a blade spinning around 5000 times per minute will not exhibit a crooked cut as the result of blade wobble or such change in width, because the all the widths will have been gone thru 5000 times and the cut will be straight and as wide as th widest wobble.

What is probably heppening and you don't say which fence you are using,
is that your workpiece is wandering from the fence. there's many ways this can happen, I discuss most of them under either the rip fence qusetions or the SMT fence questions in the BT3 FAQ.

[vaking]

Please also check the blade is vertical and you are not making a bevel cut.

[LarryG]

I'm still not clear whether the cut is curved slightly along its length, or beveled slightly across the material's thickness, but either way my first suspect would be a misaligned rip fence. A rip fence that is slightly pinched in at the rear can produce either result.

My second suspect, and no offense is intended here, would be technique. A lot of people watch the blade as they make a cut. If that's what you're doing, try watching where the workpiece meets the fence. If you concentrate on maintaining solid contact here throughout the cut, the blade will take care of itself. (Obviously you will want to remain fully aware of exactly where the you are relative to the blade at all times, but you can do that with your peripheral vision and/or quick glances.)

[meika123]

I think I would get a framing square, hold one edge against the saw table and bring the other edge up against the blade. Check to see if the blade is perfectly vertical.
Also, do the same thing with the fence, and check it's vertical. Otherwise, as others have said, remove the blade, washers, and all to see if it is clean.
Let us know what you find.

Dave in NC